This invention relates to automatic chemical testing apparatus, and more particularly to means for dispensing reagents therein.
The present invention relates to an improvement to the type of apparatus disclosed in U.S. Pat. No. 3,723,066 issued to John J. Moran on Mar. 27, 1973, assigned to the assignee herein, the disclosure of which is incorporated herein by reference. U.S. Pat. No. 3,728,079 issued to John J. Moran on Apr. 17, 1973, also commonly assigned which describes the operation of the type of chemical analyzer contemplated as the context for the present invention. The disclosure thereof is also incorporated herein by reference. In automatic chemical analyzer, samples to be analyzed, for example human serum, are added to reaction containers, reagents are combined therewith, and the reacted contents of the reaction container are analyzed for the present of a particular substance. It is necessary to dispense accurately a given amount of reagent to each sample container. Precision of amounts to be dispensed must be on the order of microliters. Another way in which pumping and dispensing systems in automatic chemical analyzers are distinguished from pumping and dispensing systems in general is that it is very important to have a limited amount of dead volume, i.e. volume remaining in pumping means after a pump stroke. It is necessary to rinse old reagent from pumping means upon a new period of analyzer usage commencing after a period of non-usage. Simply flushing water through reagent lines at the end of a period of usage is very expensive in terms of the skilled operator labor involved. Further, water remaining in hydraulic lines would dilute reagents being pumped at the beginning of a next period of usage. Further, the reagents in chemical analyzer systems tend to be quite expensive compared to fluids pumped by dispensing and pumping systems in general.
It is also desirable to provide for convenient, efficient mounting of pump means in a chemical analyzer and cooperation of pump means with fluid paths.